The present invention relates to a color filter dyeing apparatus for dyeing a color filter formed on a substrate, such as a glass substrate or a semiconductor substrate. The invention is particularly suitable for dyeing an on-chip filter.
Conventionally, in the process of fabrication of on-chip-type color filters for a solid-state imager or color filters for a liquid crystal coler TV set, substrates on which layers or patterns (which are to be dyed afterward) of a material such as gelatin and casein are soaked in a dyeing solution bath. Tens of substrates are processed at a time, i.e., in a batch. As an example, the substrate process for dyeing a color filter on a semiconductor substrate forming a solid state imager is shown in FIG. 9. Usually each batch consists twenty five substrates, which are soaked in the dyeing solution (step 51). The substrates are then rinsed (step 52) to prevent residue of unnecessary dye on the substrate. The substrates are then dryed (step 53) by spin dry method or the like.
FIG. 10 shows an example of a conventional color filter dyeing apparatus for dyeing color filters i.e., layers or patterns to be dyed which themselves are not illustrated as such and which are formed on the substrates 6. The dyeing apparatus comprises a dyeing solution bath 31 filled with a dyeing solution 5, a recovery bath 32 for recovering or collecting the dyeing solution which have overflown the dyeing solution bath 31, and a circulating pump 33 for feeding the dyeing solution from the recovery bath 32 to the dyeing solution bath 31. A substrate support member 34 holds the substrates in alignment. Several to several tens of substrates can be held at the same time. A transfer member 35 for transferring the substrates is mounted to the support member 34. A draining board 56 is disposed at the bottom of the dyeing solution bath 31.
In operation, the dyeing solution bath 31 is continuously fed with a new dyeing solution 5 by means of the circulating pump 33. The dyeing solution having overflown is recovered into the recovery bath 32. The dyeing solution 5 in the recovery bath 32 is again fed back by the circulating pump 33 and is fed into the dyeing solution bath 31. Thus the dyeing solution 5 is always circulated. The draining board 36 diverges the flow of the dyeing solution flowing through the inlet into the dyeing solution bath 31 thereby distributing the flow throughout the dyeing solution bath 31. It also prevents the support member 34 from being too low or approaching the bottom too closely. The support member 34 on which the substrates 6 are arranged is transferred, manually or by means of a transfer mechanism not shown, into the dyeing solution bath 31. The color filters on the substrates are soaked in the dyeing solution 5 and are thereby dyed. Upon expiration of a predetermined time, the support member with the substrates are transferred out of the dyeing solution bath 31, in a manner similar to that in which it was transferred in, and is then transferred to a rinsing step 52.
Shortcomings of the above-described conventional apparatus are: (i) that continuous processing cannot be made; (ii) that the concentration and characteristics of the dyeing solution vary through repeated use of the dyeing solution, so that the characteristics (particularly the spectral characteristics) of the resultant color filters fluctuates; and (iii) that, when the agitation or stirring of the dyeing solution in the dyeing solution bath is insufficient, the uniformity in the temperature, pH and the like deteriorates and the characteristics of the resultant color filters may vary depending on the position within the support member.